Pfizer Halts COVID-19 Trial, Citing Data Hurdles, Amid Regulatory Uncertainty

By James Jarvis / April 2, 2026 at 5:48 PM

Pfizer and BioNTech have halted a large U.S. trial of their updated COVID-19 vaccine in adults ages 50-64, citing low enrollment that prevented the study from generating sufficient data, according to a letter to investigators first reported by Reuters.


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